The present invention relates to moving object identification systems and in particular to a closed circuit television system for object identification utilizing motion compensation.
In order to keep track of the vast number of freight cars which travel along the nations railways system, each car is assigned a number which appears prominently on the cars. Over the years various systems have been proposed to facilitiate the reading of the numbers by railway personnel. In one such system, it has been proposed to utilize closed circuit television to view the cars passing a sensing station. The television camera is connected to a monitor in a control tower (directly or through a tape recorder) and an inspector in the tower reads the identification number of the cars passing the inspection station.
While the above system would work effectively if the cars stopped or moved through the inspection facility at slow speeds (i.e., less than 15 mph). A major problem is encountered when a large number of trains pass through the inspection stations at speeds in excess of 15 miles per hour. At 15 miles per hour, a car moves approximately 4.4 inches in the 1/60 second exposure time of a TV field. This motion is sufficient to produce a significant blur to make reading of the identification number of the freight car difficult for an inspector watching a TV monitor. At speeds even slightly in excess of 15 mph the motion blur becomes highly pronounced and sufficiently intolerable so that it becomes impossible to read the numbers from the monitor.
To compensate for the motion blurring problem discussed above, it has heretofore been proposed to provide a shutter in the optical path of the TV camera to effectively serve to reduce the exposure time to a fraction of a TV field and in effect stop the motion of the train as imaged by the TV camera. The shutter exposure time may be fixed or synchronized to the train speed. In either case, the use of the shutter serves to reduce the light entering the camera optical path and in many instances the reduction of light must be compensated for by the use of artificial lighting. This provides for an expensive and complex system.
In view of the above, it is the principal object of the present invention to provide a closed circuit television object identification system having improved motion compensation.
A further object of the present invention is to provide such a system in which motion compensation is attained with virtually no sacrifice of the sharpness or quality of the resultant image.
A still further object is to provide a system which utilizes conventional components and which may readily be implemented and retrofitted into existing railroad facilities.